Various types of rotation detectors have conventionally been proposed. The following Patent Literature 1 describes one example of the conventional rotation detectors.
One of the various types of rotation detectors described in Patent Literature 1 includes: a magnet forming a magnetic field between the magnet and a rotary member; a magnetism detection element disposed in the proximity of the magnet to detect that the magnetic field generated by the magnet is varied due to rotation of the rotary member; and a signal processing circuit for processing a signal from the magnetism detection element.
The signal processing circuit is constructed with various parts mounted on a board. Then, a resin is filled within a recess portion of a casing in a state in which the signal processing circuit (that is to say, the board on which the parts are mounted) is accommodated. Thus, the signal processing circuit is sealed and coated with the resin.
Patent Literature 1: A Japanese Utility Model Registration Application Publication (Jikkai) No. Heisei 5-14829.